Semiconductor integrated circuits or chips are ubiquitous in nearly every modern product. Whether used for a smart phone, a television, a washing machine, or another common or specialty product, chips are used for control, communication, networking, safety, and other functions that range anywhere from very basic to intricate and complex. Regardless of the application, the development cycle, which is the time from design to commercial availability of a product, is important for any business or government entity. In competitive areas such as consumer electronics, reducing the development cycle can make the difference between a successful product, versus a product that arrives on the market too late to be a competitive product.
Because of the intricacy of the chips used in these and other products, modeling and simulation techniques are repeatedly applied to the circuit designs throughout the design processes. The models that are generated for the designs describe the chips at various levels of design abstraction. The levels of abstraction, while arbitrary, are used to describe the circuit at varied levels of detail, from wiring lists or netlists, to logical connections, to structure, and to behavior, among many others. The levels of abstraction are used to control the complexity of the designs as the designs are modeled and simulated. In some cases, simulation can reduce or even eliminate the need for extensive prototyping of circuits. Thus simulation can reduce development time required to get a product to market, as well as reducing development costs by finding design issues earlier in the product development process.
Netlists and wiring lists provide a description of the connectivity of an electronic circuit. The netlist can include a list of terminals/pins of the electronic components in a circuit, as well as a list of the electrical connections that interconnect the terminals. The different types of circuits that can be represented by netlists include analog, digital, and mixed-signal. The mixed-signal circuits comprise both analog and digital portions that are coupled to each other.
Simulations can vary in sophistication from pure logical simulation that assumes an ideal case in terms of switching times and propagation delays, to a complex simulation that accounts for various device parameters such as gate widths, semiconductor material characteristics, ambient conditions, and the like. Hardware Description Language (HDL) is a language that can be used to describe the structure and behavior of an electronic circuit, and is particularly useful for digital logic circuits. HDL provides a temporal dimension to simulate the behavior or state of circuits as a function of time. Libraries including basic circuits, standard cells, and the like can be combined to make highly complex circuits. Simulation can be part of an Electronic Design Automation (EDA) toolchain and process. It enables designers to try various combinations of circuits without the expense of actual fabrication. At the transistor level, various parameters such as device width, voltage thresholds, and transition times can be included in the simulation. These tools enable reduced development cost and time that is essential given the competitive nature of today's electronics industry.